Method of lubrication and lubricant therefor



-. Walter ill. Hudson, @hicago, llll:

No Drawing. Application April 6, 19%, Serial No. 719,407

7 v Claims.

This invention relates to a method of lubrication, particularly for rollnecks in rolling mills,-

tion of such machinery has been extremely inemcient, and any attempt atemciency has m suited in the wastage of enormous quantities oflubricant.

It has been heretofore considered impossible to make the greases softer,since for a particular lubrication, a grease of definite hardness isrequired to stand the particular load and conditions. Non-lubricatingmaterial such as a high melt point asphalt is required on account oi thehigh temperature conditions. The greases used for this type of work havebeen soda or soda lime soap base greases, but it has heretofore not beenpossible to use large amounts of grease material.

In accordance with this invention, such greases are rendered more fluidby the incorporation of certain organic solvents, to such a point thatthey may be applied readily to the spot to be lubricated, for example,through an autotic or pressure lubrication system. The solvent ispreferably so chosen that when the grease reaches the point oflubrication, the temperature present will cause the solvent toevaporate, and the grease will then regain its former characteristics.

The solvent chosen must be one which does not a cause a breakdown of thegrease initially, or materially affect its lubricating properties, andshould have a boiling point above normal atospheric conditions.

Clearly the solvent should not evaporate under the pressure andtemperature conditions in the lubricant-feeding mechanism, but shouldhave a simciently highboiling point as to maintain the necessaryfluidity until the point of lubrication has been reached.

For example, a sodium base grease may be prepared in the orry mannercontaining to 50% of a soda soap, such as oleate, stearate or the like(preferably tallow fat acids), and the balance mineral oil of thedesired viscosity. A typical grease will contain 30% sodium soap and Wu;of a vy i, i ed cylinder stock lJt ilfll eral oil having a viscosity of200 Sayboldt at 210 F. Such a grease will be extremely hard. Theproportion of tallow or soap is far higher in these greases than waspossible under prior practice, and the greases therefore have aconsiderably higher melting point initially than for- Qmerly was thecase for similar operating conditions.

The fluidity of such hard grease may then be modified by incorporating asolvent which will not destroy t e grease structure. For example, butylcarbitol, (monobutyl ether of diethylene glycol), carbitol, (monoethylether of diethylene glycol), ethylene dichloride, or dichlorethyl ethermay be used, preferably in proportions of from 1% upwards. Normally notmore than 5% need be used. With the particular sodium soap described, 2of butyl carbitol is preferred. The addition of this amount of solventrenders the grease soft enough to be applied by ordinary mechanicallubrication methods, but does not afiect its lubricating properties.

By proper choice of solvents, one may be selected which will evaporateunder the particular bearing temperature encountered, and will thusproduce a grease having the original consistency and othercharacteristics of the initial product. For high temperaturelubrication, butyl carbitol, having a boiling point of 431 F. ispreferable. The carbitol boils at 388 F., the dichlorethyl ether at 350F., and the ethylene dichloride at 188 F. and these solvents may be usedfor conditions suitable to their particular boiling points.

Upon reaching the point of lubrication, the solvent evaporates andproduces. a grease of the original consistency. However, even if thesolvent does not evaporate, the efiectiveness of the grease is notsubstantially impaired.

In the case of a lime soap grease, either an anhydrous or a hydratedgrease may be used. In the case oi the anhydrous grease, a couplershould be used such as described in my co-pending application Serial No.412,930.- The grease in general will contain 5 to 50% of a lime soapsuch as lime tallow soap, and the remainder consists of a mineral oil.For example, a hard grease may be prepared from lime tallow soap and 80%or a heavy mineral oil such as was described in connection with the sodasoap grease. With this grease may be incorporated a small amount oi acoupler to prevent segregation, and the fluidity of the grease may thenbe modified as desired by incorporation of a minor percentage of asolvent such as a phenyl chloride, including monocr 1-1.4 w orthodichior z:

iii

trichlor benzene, or solvents such as ethylene dichloride, dichlorethylether, trichlor ethylene or the like. 1 to 5% is normally suflicient,and 2 of monochlor benzene is preferred in the specific greasedescribed.

As with the soda soap, the particular solvent may be chosen inaccordance with the temperature to be encountered. Ethylene dichloridehas a boiling point of 188 F; dichlorethyl ether of 350 F; ortho dichlorbenzene of 354 F., monochlor benzene of 270 F., and trichlor benzene of419 F. and trichlor ethylene of 188 F.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, but the appended claims should be construed as broadly aspermissible, in view of the prior art.

I claim:

1. The method of lubricating a hot roll neck bearing normally requiringlubricating greases which are hard at atmospheric temperatures, whichcomprises adding to such a hard grease a small proportion of a greasecompatible solvent volatile at the operating temperature of the bearing,said solvent being a hydrocarbon or derivative thereof and having aboiling point high enough that it does not evaporate under thetemperature and pressure conditions of the lubricant feeding mechanism,the proportion of the solvent being large enough to soften the greasesufliciently to be applied by mechanical lubrication systems and beingsmall enough that the grease structure is retained in the softenedgrease, and mechanically applying the grease to the bearing, where theheat of operation of the bearing evaporates the solvent and produces agrease inherently of the original consistency.

2. The method as set forth in claim 1, in which the solvent has aboiling point of at least 180 F.

3. The method as set forth in claim 1, in which the solvent is of theorder of 1-5% of the lubricant.

4. The method as set forth in claim 1, in which the grease is a sodasoap grease and the solvent is selected from the class consisting ofmonobutyl ethyl of diethylene glycol, monoethyl ether of diethyleneglycol, ethylene dichloride and dichlorethyl ether.

5. The method as set forth in claim 1, in which the grease is a limesoap grease and the'solvent is selected from the class consisting ofphenyl chlorides, ethylene. dichloride, trichlor ethylene, anddichlorethyl ether.

WALTER D. HODSON.

